Birth Control Pills (Oral Contraceptives)

What are birth control pills?

Birth control pills (oral contraceptives) are a method of
birth control that uses hormones to prevent pregnancy.
The man-made female hormones in the pills change a
woman's natural hormone levels and prevent her ovaries
from releasing an egg each month. The hormones also help
prevent pregnancy in 2 other ways. They cause a
thickening of the mucus on the cervix and they change the
lining of the uterus. The thickened mucus on the cervix
makes it hard for sperm to enter the uterus. The change
in the lining of the uterus helps prevent a fertilized
egg from attaching to the uterus.

The most commonly used pills are "combined" pills. They
contain man-made forms of 2 hormones: estrogen and
progesterone. There is also a progesterone-only pill (the
mini-pill), but it is not as effective and causes a lot of
blood spotting between menstrual periods.

How are the pills used?

The combined pills usually come in a package of 28 pills.
They are also available in 21-pill or 91-pill packs. You
and your health care provider will decide which type of
package is best for you. Your provider will probably advise
you to start taking the pills on the Sunday after your
period has started or on the first day of your next period,
depending on your preference.

Try to take your pill at the same time every day. This
will help you remember to take the pills. It will also
help keep hormone levels steady.

Use a backup method of birth control (such as condoms and
spermicide) until you have been taking the pills for 2
weeks.

Use condoms, even though you are taking birth control
pills, for protection against sexually transmitted
disease unless you have a long-term, single-partner
relationship.

If you have bleeding between periods for several cycles
you may need a different pill. Call your health care
provider for an appointment.

Any time you are seen for medical reasons, be sure to
mention that you are taking birth control pills. This is
particularly important if you are admitted to the
hospital or having surgery.

21-day pill pack

If you are using the 21-pill pack, take 1 pill every day for
3 weeks. Stop taking the pills for 7 days and then start a
new pack. Your period comes during the week that you are
not taking pills.

28-day pill pack

If you are using the 28-day package, take 1 pill every day
for 4 weeks and then start a new package the next day. The
last 7 pills are inactive and contain no medicine for birth
control. They just keep you in the habit of taking a pill
every day. Your period comes during the week that you are
taking the last 7 pills.

91-day pill pack

If you are using the 91-day pill pack, you take 1 pill of
active medicine every day for 12 weeks (84 days). Then
you take 1 inactive pill every day for 1 week (7 days).
You will have your period while you are taking the
inactive pills. This means that you have a period just
once every 3 months.

What if I forget to take a pill?

Your risk of pregnancy increases when you miss any pills.

If you forget 1 pill, take it as soon as you remember, even
if it is the next day. Take the next pill on time.

If you miss 2 or more doses in a row, see the information
sheet that comes in the medicine package or ask your health
care provider what to do. Use an additional method of
birth control, such as condoms or spermicide, until your
next period starts.

What are the benefits?

The benefits are:

Birth control pills are 92 to over 99% effective in
preventing pregnancy. This means that, for every 100
women who use the pills for a year, 8 or fewer women
will become pregnant by the end of the year.

You do not have to interrupt lovemaking to use a birth
control device or spermicide.

Periods become regular and usually lighter. Menstrual
cramps may be less severe.

Long-term use lowers the risk of cancer of the ovary.

Birth control pills may reduce symptoms of
premenstrual syndrome (PMS).

What are the disadvantages?

One disadvantage of birth control pills is that you must
remember to take a pill every day.

The pills usually have no side effects, but sometimes they
cause side effects such as:

irregular menstrual bleeding or spotting for the first
few months after you start birth control pills

dizziness

nausea and vomiting

swelling of your hands or ankles

pain, swelling, or tenderness in the abdomen

breast swelling or tenderness

more appetite and weight gain

trouble sleeping, weakness, lack of energy, fatigue, or
depression

headaches

vaginal infection (usually yeast)

allergic reaction, rash, itching

amenorrhea (absence of menstrual period)

less interest in sex

changes in hair growth patterns

vision or contact lens problems

yellowing of the skin or whites of the eyes (jaundice).

You should not smoke. Smoking increases the risk of
serious side effects, such as heart attack, stroke, and
blood clots. This is especially true if you are over 35
years old and smoke 15 or more cigarettes a day.

Birth control pills do not protect you from sexually
transmitted diseases such as AIDS. Latex or polyurethane
condoms are the only safe way to protect against AIDS.

Some medicines can affect the way birth control pills work
in your body. Birth control pills may not keep protecting
you against pregnancy if you are taking certain antibiotics
or medicines for seizures or fungal infections. Tell your
health care provider about all medicines or natural remedies
you are taking. You may need to use an additional form of
birth control while you are taking these medicines.

When should I call my health care provider?

Call your provider right away if you have:

sharp chest pain or sudden shortness of breath or are
coughing up blood

sudden severe headache or vomiting, dizziness or
fainting, or problems with vision or speech

sudden partial or complete loss of vision

yellowing of the skin or whites of the eyes (jaundice),
especially with fever, tiredness, loss of appetite, dark
urine, or light-colored bowel movements

unexplained pain, weakness, or numbness in the calf of
one of your legs

severe pain, swelling, or tenderness in the abdomen.

Call during office hours if you have:

problems with your menstrual periods, such as bleeding
between periods, prolonged periods, or missed periods, or
you think you are pregnant

This content is reviewed periodically and is subject to
change as new health information becomes available. The
information is intended to inform and educate and is not a
replacement for medical evaluation, advice, diagnosis or
treatment by a healthcare professional.